The present invention generally relates to hand tools, and more particularly, to power reciprocating hand tools.
Reciprocating tools that are motor driven, such as saber saws, larger reciprocating saws and the like are usually driven by electric motors that have a rotating output shaft. Therefore, this rotating motion must be translated into reciprocating motion for moving a saw blade or the like in a reciprocating manner. While various types of mechanisms have been known in the art for translating the rotation motion into reciprocating motion, one common type of motion conversation mechanisms are wobble plate drives. A wobble plate drive shaft is typically connected to the motor through a gear arrangement that usually functions to reduce the speed of rotation of the motor output shaft and the wobble plate drive causes a wobble arm to reciprocate in a path that is parallel to the motion of the saw blade or the like which the wobble plate drive is used for. The blade of a reciprocating saw is mounted in a blade clamping mechanism that is located at the end of a spindle, the other end of which is operatively connected to a wobble arm.
In some prior art wobble plate drives, the spindle has a rectangular or square cross-section that is located in a rectangular or square opening to restrain the spindle from any movement other than reciprocating movement. While these noncircular cross-section spindles operate in a desirable manner, the noncircular cross-section increases the cost relative to a tubular spindle construction which is more desirable. However, a tendency of wobble plate drives for driving a spindle is to exert forces on the spindle which tend to cause it to rotate. Since rotation of the spindle would necessary rotate the reciprocating blade, such rotation must be prevented.